On Fri, 2017-09-08 at 15:57 +0200, Borislav Petkov wrote: > On Fri, Aug 18, 2017 at 05:27:52PM -0700, Ricardo Neri wrote: > > > > String instructions are special because, in protected mode, the > > linear > > address is always obtained via the ES segment register in operands > > that > > use the (E)DI register; the DS segment register in operands that > > use > > the (E)SI register. Furthermore, segment override prefixes are > > ignored > > when calculating a linear address involving the (E)DI register; > > segment > > override prefixes can be used when calculating linear addresses > > involving > > the (E)SI register. > > > > It follows that linear addresses are calculated differently for the > > case of > > string instructions. The purpose of this utility function is to > > identify > > such instructions for callers to determine a linear address > > correctly. > > > > Note that this function only identifies string instructions; it > > does not > > determine what segment register to use in the address computation. > > That is > > left to callers. A subsequent commmit introduces a function to > > determine > > the segment register to use given the instruction, operands and > > segment override prefixes. > > > > Cc: Dave Hansen <[email protected]> > > Cc: Adam Buchbinder <[email protected]> > > Cc: Colin Ian King <[email protected]> > > Cc: Lorenzo Stoakes <[email protected]> > > Cc: Qiaowei Ren <[email protected]> > > Cc: Arnaldo Carvalho de Melo <[email protected]> > > Cc: Masami Hiramatsu <[email protected]> > > Cc: Adrian Hunter <[email protected]> > > Cc: Kees Cook <[email protected]> > > Cc: Thomas Garnier <[email protected]> > > Cc: Peter Zijlstra <[email protected]> > > Cc: Borislav Petkov <[email protected]> > > Cc: Dmitry Vyukov <[email protected]> > > Cc: Ravi V. Shankar <[email protected]> > > Cc: [email protected] > > Signed-off-by: Ricardo Neri <[email protected]> > > --- > > arch/x86/lib/insn-eval.c | 26 ++++++++++++++++++++++++++ > > 1 file changed, 26 insertions(+) > Reviewed-by: Borislav Petkov <[email protected]>
Thanks for your review! BR, Ricardo
